Recovery Map for Fermionic Gaussian Channels

A recovery map effectively cancels the action of a quantum operation to a partial or full extent. We study the Petz recovery map in the case where the quantum channel and input states are fermionic and Gaussian. Gaussian states are convenient because they are totally determined by their covariance matrix and because they form a closed set under so-called Gaussian channels. Using a Grassmann representation of fermionic Gaussian maps, we show that the Petz recovery map is also Gaussian and determine it explicitly in terms of the covariance matrix of the reference state and the data of the channel. As a by-product, we obtain a formula for the fidelity between two fermionic Gaussian states. We also discuss subtleties arising from the singularities of the involved matrices.Comment: 13 pages and 11 pages of appendices. Updated references and footnotes in v2. Updated for a new paragraph of twisted recovery map and change of format in v

Inactive lifestyle in adults with bilateral spastic cerebral palsy

Objective: To quantify the level of everyday physical activity in adults with bilateral spastic cerebral palsy, and to study associations with personal and cerebral palsy-related characteristics. Participants and methods: Fifty-six adults with bilateral spastic cerebral palsy (mean age 36.4 (standard deviation (SD) 5.8) years, 62% male) participated in the study. Approximately 75% had high gross motor functioning. Level of everyday physical activity was measured with an accelerometry-based Activity Monitor and was characterized by: (i) duration of dynamic activities (composite measure, percentage of 24 h); (ii) intensity of activity (motility, in gravitational acceleration (g)); and (iii) number of periods of continuous dynamic activity. Outcomes in adults with cerebral palsy were compared with those for able-bodied age-mates. Results: Duration of dynamic activities was 8.1 (SD 3.7) % (116 min per day), and intensity of activity was 0.020 (SD 0.007) g; both outcomes were significantly lower compared with able-bodied age-mates. Of adults with cerebral palsy, 39% had at least one period of continuous dynamic activities lasting longer than 10 min per day. Gross motor functioning was significantly associated with level of everyday physical activity (Rs -0.34 to -0.48; p≤0.01). Conclusion: Adults with bilateral spastic cerebral palsy, especially those with low-level gross motor functioning, are at risk for an inactive lifestyle

Functional status and dependency of stroke patients 5 years after clinical rehabilitation

Objectives. A population of stroke patients is described five years after discharge from a rehabilitation centre. The aim of the study was to obtain insight in a) long-term changes in functional capacities; b) disability and the perceived problems; and c) the sort of help needed. Methods. Fifty stroke patients (mean age 63 years) treated between January 1986 and October 1990, were visited at home by a physician. Four functional measurements were used; the newly developed Rehabilitation Activities Profile, the Barthel Index, a four-item (Barthel Index) subscore (B4), and the Frenchay Activities Index. Results. There was some disability in communication, but in this group much help was needed concerning mobility. The majority was independent in personal care, but frequently needed help with household activities. Most patients experienced disabilities with occupational and leisure activities and many problems were encountered in relations. Basic functional items (B4) did not seem to have changed. The majority of the patients (82%) was living at home, but a considerable part was depending on home care (40%), physical therapy (26%), home adjustments (50%) and/or appliances (50%). In spite of the complexity of the problems only 12% of the patients was seen regularly by their rehabilitation physician. Conclusion. From this selected group of stroke patients we learned that treatment strategies and research concerning rehabilitation of these patients should be directed towards mobility, daily activities and personal relations